well, i have a 3 inch lift with 31 inch cooper discover stt's. i get about 13 mpg at 60 mph.. i have the 4.0 but still i feel as though i should be getting better gas mileage, i seafoamed it not long ago.. any suggestions? also it has 151k and its a 98 limited.

 

All around good maintenance will do wonders! Replacing all the oils in your drive train (motor, trans, t-case, & gear oil). also new plugs/wires, air filter, fuel filter, & a good cleaning of the throttle body! Seafood is a good start to clean out the injectors, but I like to run Lucas fuel treatment every other time I fill up! Do all of this & report back with your new mpg?

 

im also replacing the oil, water pump, harmonic balancer and thermostat next weekend.. so this should be good. all the diff fluid is fine and the t case fluid is good enough.. but ill put something into her for gas treatment.

 

Have you changed the gear ratio? This would help put the engine back into the original power band that is was created for. http://sierrabronco.com/TireGearRatio.htm

If you know your current gear ratio compare it to a 28" tire (stock) and see what the RPM reading is. Then go to the 31" tire size and go across until you reach an RPM similar to the original, go up to find the gear ratio that you need.

If you have not changed the gear ratio.. when you calculated the MPG did you adjust the calculations for the difference in tire size? http://www.performanceprobe.com/inde...calc&page=tire

If you go from a 28" tire to a 31" tire, your speedo and odometer will be off. Your odometer would read 9055 miles when you have actually gone 10K miles or a difference of 945 miles, about 9%. When your speedometer reads 54mph, you are actually going almost 60mph.



If you are cruising around doing 65 in a 60 thinking you are allowed 5 over... you are really doing closer to 70....= ticket.

 

Regearing for 31"s is a waist of money. If you had or found a set of axles with 4.10s in them I would say swap them in but don't pay 2k for gears u will want to upgrade later when u go up to 33"s or 35"s.

 

What is seafood, fish like it but I didn't know injector's did too. lol just pickin'.

 

Thanks alot man i have always wondered what the ratio between that was. And yes the gear ratio is stock.. but yeah, i dont think im going to invest in gearing it just yet.
PS. i have the limited so theres in information center on the upper council that gives me instant mpg, DTE, temp and direction and two additional odometers.

 

the info that it gives is off the orginal set-up and will be wrong. If you have
or can borrow a gps try that for mph.

 

Beat me to it lol!

Seafoam is good stuff. 1/2 can in the brake booster line to the TB, the other half in the gas tank. You can put it in the oil,
only if it's absolutely filthy though and a rebuild is imminent IMHO.
If you really wanna do it, ONLY put it in the oil for a few minutes. It cleans better than a quart of tranny fluid in there will, but on that token, It'll free up so much goop it could actuall clog passageways though, so only use it in the oil if you have to, though I wouldn't.

I'm a fan of Marvel Mystery Oill every change too. Seems to quiet down stuff.
Gonna try Lucas again soon, though last time I never noticed as much difference as with MMO.

 

ok guys call me a super noob but how do you check tcase fluid?

 

Take out the top bolt (fill bolt) and stick a finger in their.

 

Take the top plug out stick your finger in it and see if you can feel any fluid. Then look at it to see if its clean